OAKLAND -- Yes, the A's get excited thinking what the addition of Jon Lester to the rotation could mean in the postseason.

That, however, was not what drove general manager Billy Beane to give up left fielder Yoenis Cespedes to acquire Lester from the Red Sox shortly before the July 31 non-waiver Trade Deadline.

Beane, as much as anyone, knows not to take anything for granted.

This, after all, is a franchise that hasn't won a World Series since 1989 and hasn't even played in one since 1990. Oh, the A's have had their chances. They have advanced to the postseason eight times in the last 23 years. They, however, were eliminated in the first round seven times, and the one time they advanced, they were swept by Detroit in four games in the 2006 American League Championship Series.

Oh, and then there was that 2004 season when the A's finished one game back of the division-champion Angels, who won 10 of the 19 regular-season games between the two teams that year.

And so for all the media hype about Beane being focused on October when he landed Lester, the truth of the matter is Beane and the A's were more concerned about August, at least for the time being.

As manager Bob Melvin put it, "we're trying to get there" to the postseason.

"There are some really good teams in our division," he said. "We were trying to get the best mix we could."

Lester is awful good, and he made a statement in the AL West race on Saturday night, pitching seven strong innings, which allowed the A's to pull out a 2-1 victory against the Angels. The A's, rebounding from a 1-7 road trip that knocked them out of the division lead, have now won back-to-back games and head into Sunday's series finale tied for first place with the Angels.

Lester had a no-decision on Saturday -- reliever Luke Gregerson was credited with the victory when Coco Crisp scampered home from third on a Joe Smith wild pitch with two out in the eighth to break the 1-1 tie -- but the A's are 4-1 in the five quality starts he has made for them and he does have a 2.60 ERA in that span.

No surprise.

Yes, he is 6-4 with a 1.97 ERA in 11 career postseason starts, 3-0 in the World Series, including winning two starts and allowing one run in 15 1/3 innings in the Red Sox championship effort against the Cardinals last year.

That, however, is not the whole story. The 30-year-old left-hander is 42-22 in August/September during his big league career. The A's also have won all three games he has started for them at O.co Coliseum this month, during which he has allowed four earned runs in 22 2/3 innings.

"He brings total tenacity," said Melvin. "He keeps guys on their toes. He works quick. You can feel the intensity behind him. When you have a big game, he's the guy you want on the mound."

What is even more important is that when a team has a big game, Lester is the guy who wants to be on the mound.

"No matter what the expectations are that people put on me, they are not going to be as high as the expectations I have for myself," said Lester. "I expect myself every time out to throw nine shutout innings, whether it's April or October."

He came close on Saturday.

With the help of several big defensive plays, Lester carried a 1-0 lead into the seventh inning, having allowed only one Angels player to get into scoring position -- Erick Aybar bunting for a two-out single in the second and advancing on a walk to Chris Iannetta. Lester then struck out Gordon Beckham, looking.

After David Freese was thrown out trying to stretch a leadoff single in the top of the seventh, Howie Kendrick doubled and scored on Aybar's ensuing single before Lester finished his night by getting a groundout from Iannetta and fly ball to center from Beckham.

"After the game is over with, it is fun," Lester said of the emotions of pitching in a meaningful August game. "But when you are going through it, you are competing and trying not to make mistakes like I did in the seventh. Obviously, I was able to minimize the damage there."

But then that's why he is in Oakland, to minimize any damage.

The A's had made the first significant trade of July when they sent a package of prime prospects to the Cubs on July 5 for right-handed starters Jeff Samardzija and Jason Hammel. Samardzija has given the A's a chance in the bulk of his nine starts -- they are 6-3 even though he is 3-3 -- but Hammel has struggled, going 1-5 with a 6.75 ERA in seven starts with the A's, and he could find himself moved out of the rotation down the stretch.

That's why the A's were willing to make that additional headline-grabbing move on July 31.

They know there is a pennant at stake. They know they need help to claim it.

And Lester is happy to be the guy they turned to.

Being in a pennant race was a blast last year, and it hasn't lost any of the excitement this time.

"You don't have the distraction of losing," he said of how winning helps ease the adjustment to a new team. "These guys obviously have a good thing going. As the new guy coming in you don't want to mess it up."

Don't worry.

Lester hasn't.

Quite the contrary.

He has enhanced the good thing the A's have going.

Tracy Ringolsby is a columnist for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.